I'd like to preface this by saying I graduated a while ago. It's possible that the school has changed significantly since then so take what I say with a grain of salt. Also, I made quite a few mistakes while there. Columbia College is a giant hub that draws in everybody from the Midwest. I feel like I know more people from Michigan than anywhere else in the world. You meet a lot of people in undergrad. Tons of students and they're all pipelined out to Los Angeles. That said, the alumni coordination leaves a little to be desired.
The big reason to go is tons of access to equipment and the ability to wheel around town and shoot whatever you want during independent study. It's an excellent trade school for its combination of hands-on experience and big alumni class. Go for an undergrad education, a solid bedrock to be followed up with an MFA. It is not a great school for writing and directing. That said, Columbia started up its Second City Program as soon as I left which likely would've been a game changer for me if it existed while I was there.
You have the ability to make an undergrad thesis with a lot of freedom. The thesis advisors aren't very hands-on. They have a Practicum Program that when I was there seemed like a great idea, designed in the style of AFI but it wasn't there in execution. Hopefully it's improved since then. It's a great idea. When I was there, it was a chaotic school without much direction and a lot of kids running around with cameras, shooting. Take all of this with a grain of salt.